For this study we will enroll 48 women (24 African American and 24 Caucasian women). To minimize the effect of age and menopause, we are enrolling women between the ages of 18 and 49 years. The study will involve several outpatient visits to the NIH Clinical Center. The first visit will be a screening to determine eligibility. At the second visit a test will be performed to measure insulin resistance. This test is called a frequently sampled intravenous glucose tolerance test. The third visit will be for the test meal. Before and at 2, 4 and 6 hours after the meal, blood will be drawn and vascular function measured. Vascular function is determined by taking blood pressure and then measuring blood flow in the arm with ultrasound. It is possible that individual differences in diet could affect the results of the vascular study on the day of the test meal. Therefore for 7 days prior to the test meal, the NIH Clinical Center will provide to each participant all their meals in the form of either trays or meals in a box. These meals will consist of the typical American diet and be 33% fat, 15% protein and 52% carbohydrate. In designing these meals, the dietician will take into account individual food preferences. In this first year we wrote the protocol, we received the Bench to Bedside Award and established the infrastructure for the clinical and basic science investigations. Recruitment is now commencing.